<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Cache
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Core.php 18951 2009-11-12 16:26:19Z alexander $
 */


/**
 * @package    Zend_Cache
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Cache_Core
{
	/**
	 * Backend Object
	 *
	 * @var object $_backend
	 */
	protected $_backend = null;

	/**
	 * Available options
	 *
	 * ====> (boolean) write_control :
	 * - Enable / disable write control (the cache is read just after writing to detect corrupt entries)
	 * - Enable write control will lightly slow the cache writing but not the cache reading
	 * Write control can detect some corrupt cache files but maybe it's not a perfect control
	 *
	 * ====> (boolean) caching :
	 * - Enable / disable caching
	 * (can be very useful for the debug of cached scripts)
	 *
	 * =====> (string) cache_id_prefix :
	 * - prefix for cache ids (namespace)
	 *
	 * ====> (boolean) automatic_serialization :
	 * - Enable / disable automatic serialization
	 * - It can be used to save directly datas which aren't strings (but it's slower)
	 *
	 * ====> (int) automatic_cleaning_factor :
	 * - Disable / Tune the automatic cleaning process
	 * - The automatic cleaning process destroy too old (for the given life time)
	 *   cache files when a new cache file is written :
	 *     0               => no automatic cache cleaning
	 *     1               => systematic cache cleaning
	 *     x (integer) > 1 => automatic cleaning randomly 1 times on x cache write
	 *
	 * ====> (int) lifetime :
	 * - Cache lifetime (in seconds)
	 * - If null, the cache is valid forever.
	 *
	 * ====> (boolean) logging :
	 * - If set to true, logging is activated (but the system is slower)
	 *
	 * ====> (boolean) ignore_user_abort
	 * - If set to true, the core will set the ignore_user_abort PHP flag inside the
	 *   save() method to avoid cache corruptions in some cases (default false)
	 *
	 * @var array $_options available options
	 */
	protected $_options = array(
        'write_control'             => true,
        'caching'                   => true,
        'cache_id_prefix'           => null,
        'automatic_serialization'   => false,
        'automatic_cleaning_factor' => 10,
        'lifetime'                  => 3600,
        'logging'                   => false,
        'logger'                    => null,
        'ignore_user_abort'         => false
	);

	/**
	 * Array of options which have to be transfered to backend
	 *
	 * @var array $_directivesList
	 */
	protected static $_directivesList = array('lifetime', 'logging', 'logger');

	/**
	 * Not used for the core, just a sort a hint to get a common setOption() method (for the core and for frontends)
	 *
	 * @var array $_specificOptions
	 */
	protected $_specificOptions = array();

	/**
	 * Last used cache id
	 *
	 * @var string $_lastId
	 */
	private $_lastId = null;

	/**
	 * True if the backend implements Zend_Cache_Backend_ExtendedInterface
	 *
	 * @var boolean $_extendedBackend
	 */
	protected $_extendedBackend = false;

	/**
	 * Array of capabilities of the backend (only if it implements Zend_Cache_Backend_ExtendedInterface)
	 *
	 * @var array
	 */
	protected $_backendCapabilities = array();

	/**
	 * Constructor
	 *
	 * @param  array|Zend_Config $options Associative array of options or Zend_Config instance
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	public function __construct($options = array())
	{
		if ($options instanceof Zend_Config) {
			$options = $options->toArray();
		}
		if (!is_array($options)) {
			Zend_Cache::throwException("Options passed were not an array"
			. " or Zend_Config instance.");
		}
		while (list($name, $value) = each($options)) {
			$this->setOption($name, $value);
		}
		$this->_loggerSanity();
	}

	/**
	 * Set options using an instance of type Zend_Config
	 *
	 * @param Zend_Config $config
	 * @return Zend_Cache_Core
	 */
	public function setConfig(Zend_Config $config)
	{
		$options = $config->toArray();
		while (list($name, $value) = each($options)) {
			$this->setOption($name, $value);
		}
		return $this;
	}

	/**
	 * Set the backend
	 *
	 * @param  object $backendObject
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	public function setBackend(Zend_Cache_Backend $backendObject)
	{
		$this->_backend= $backendObject;
		// some options (listed in $_directivesList) have to be given
		// to the backend too (even if they are not "backend specific")
		$directives = array();
		foreach (Zend_Cache_Core::$_directivesList as $directive) {
			$directives[$directive] = $this->_options[$directive];
		}
		$this->_backend->setDirectives($directives);
		if (in_array('Zend_Cache_Backend_ExtendedInterface', class_implements($this->_backend))) {
			$this->_extendedBackend = true;
			$this->_backendCapabilities = $this->_backend->getCapabilities();
		}

	}

	/**
	 * Returns the backend
	 *
	 * @return object backend object
	 */
	public function getBackend()
	{
		return $this->_backend;
	}

	/**
	 * Public frontend to set an option
	 *
	 * There is an additional validation (relatively to the protected _setOption method)
	 *
	 * @param  string $name  Name of the option
	 * @param  mixed  $value Value of the option
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	public function setOption($name, $value)
	{
		if (!is_string($name)) {
			Zend_Cache::throwException("Incorrect option name : $name");
		}
		$name = strtolower($name);
		if (array_key_exists($name, $this->_options)) {
			// This is a Core option
			$this->_setOption($name, $value);
			return;
		}
		if (array_key_exists($name, $this->_specificOptions)) {
			// This a specic option of this frontend
			$this->_specificOptions[$name] = $value;
			return;
		}
	}

	/**
	 * Public frontend to get an option value
	 *
	 * @param  string $name  Name of the option
	 * @throws Zend_Cache_Exception
	 * @return mixed option value
	 */
	public function getOption($name)
	{
		if (is_string($name)) {
			$name = strtolower($name);
			if (array_key_exists($name, $this->_options)) {
				// This is a Core option
				return $this->_options[$name];
			}
			if (array_key_exists($name, $this->_specificOptions)) {
				// This a specic option of this frontend
				return $this->_specificOptions[$name];
			}
		}
		Zend_Cache::throwException("Incorrect option name : $name");
	}

	/**
	 * Set an option
	 *
	 * @param  string $name  Name of the option
	 * @param  mixed  $value Value of the option
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	private function _setOption($name, $value)
	{
		if (!is_string($name) || !array_key_exists($name, $this->_options)) {
			Zend_Cache::throwException("Incorrect option name : $name");
		}
		$this->_options[$name] = $value;
	}

	/**
	 * Force a new lifetime
	 *
	 * The new value is set for the core/frontend but for the backend too (directive)
	 *
	 * @param  int $newLifetime New lifetime (in seconds)
	 * @return void
	 */
	public function setLifetime($newLifetime)
	{
		$this->_options['lifetime'] = $newLifetime;
		$this->_backend->setDirectives(array(
            'lifetime' => $newLifetime
		));
	}

	/**
	 * Test if a cache is available for the given id and (if yes) return it (false else)
	 *
	 * @param  string  $id                     Cache id
	 * @param  boolean $doNotTestCacheValidity If set to true, the cache validity won't be tested
	 * @param  boolean $doNotUnserialize       Do not serialize (even if automatic_serialization is true) => for internal use
	 * @return mixed|false Cached datas
	 */
	public function load($id, $doNotTestCacheValidity = false, $doNotUnserialize = false)
	{
		if (!$this->_options['caching']) {
			return false;
		}
		$id = $this->_id($id); // cache id may need prefix
		$this->_lastId = $id;
		self::_validateIdOrTag($id);
		$data = $this->_backend->load($id, $doNotTestCacheValidity);
		if ($data===false) {
			// no cache available
			return false;
		}
		if ((!$doNotUnserialize) && $this->_options['automatic_serialization']) {
			// we need to unserialize before sending the result
			return unserialize($data);
		}
		return $data;
	}

	/**
	 * Test if a cache is available for the given id
	 *
	 * @param  string $id Cache id
	 * @return boolean True is a cache is available, false else
	 */
	public function test($id)
	{
		if (!$this->_options['caching']) {
			return false;
		}
		$id = $this->_id($id); // cache id may need prefix
		self::_validateIdOrTag($id);
		$this->_lastId = $id;
		return $this->_backend->test($id);
	}

	/**
	 * Save some data in a cache
	 *
	 * @param  mixed $data           Data to put in cache (can be another type than string if automatic_serialization is on)
	 * @param  string $id             Cache id (if not set, the last cache id will be used)
	 * @param  array $tags           Cache tags
	 * @param  int $specificLifetime If != false, set a specific lifetime for this cache record (null => infinite lifetime)
	 * @param  int   $priority         integer between 0 (very low priority) and 10 (maximum priority) used by some particular backends
	 * @throws Zend_Cache_Exception
	 * @return boolean True if no problem
	 */
	public function save($data, $id = null, $tags = array(), $specificLifetime = false, $priority = 8)
	{
		if (!$this->_options['caching']) {
			return true;
		}
		if ($id === null) {
			$id = $this->_lastId;
		} else {
			$id = $this->_id($id);
		}
		self::_validateIdOrTag($id);
		self::_validateTagsArray($tags);
		if ($this->_options['automatic_serialization']) {
			// we need to serialize datas before storing them
			$data = serialize($data);
		} else {
			if (!is_string($data)) {
				Zend_Cache::throwException("Datas must be string or set automatic_serialization = true");
			}
		}
		// automatic cleaning
		if ($this->_options['automatic_cleaning_factor'] > 0) {
			$rand = rand(1, $this->_options['automatic_cleaning_factor']);
			if ($rand==1) {
				if ($this->_extendedBackend) {
					// New way
					if ($this->_backendCapabilities['automatic_cleaning']) {
						$this->clean(Zend_Cache::CLEANING_MODE_OLD);
					} else {
						$this->_log('Zend_Cache_Core::save() / automatic cleaning is not available/necessary with this backend');
					}
				} else {
					// Deprecated way (will be removed in next major version)
					if (method_exists($this->_backend, 'isAutomaticCleaningAvailable') && ($this->_backend->isAutomaticCleaningAvailable())) {
						$this->clean(Zend_Cache::CLEANING_MODE_OLD);
					} else {
						$this->_log('Zend_Cache_Core::save() / automatic cleaning is not available/necessary with this backend');
					}
				}
			}
		}
		if ($this->_options['ignore_user_abort']) {
			$abort = ignore_user_abort(true);
		}
		if (($this->_extendedBackend) && ($this->_backendCapabilities['priority'])) {
			$result = $this->_backend->save($data, $id, $tags, $specificLifetime, $priority);
		} else {
			$result = $this->_backend->save($data, $id, $tags, $specificLifetime);
		}
		if ($this->_options['ignore_user_abort']) {
			ignore_user_abort($abort);
		}
		if (!$result) {
			// maybe the cache is corrupted, so we remove it !
			if ($this->_options['logging']) {
				$this->_log("Zend_Cache_Core::save() : impossible to save cache (id=$id)");
			}
			$this->remove($id);
			return false;
		}
		if ($this->_options['write_control']) {
			$data2 = $this->_backend->load($id, true);
			if ($data!=$data2) {
				$this->_log('Zend_Cache_Core::save() / write_control : written and read data do not match');
				$this->_backend->remove($id);
				return false;
			}
		}
		return true;
	}

	/**
	 * Remove a cache
	 *
	 * @param  string $id Cache id to remove
	 * @return boolean True if ok
	 */
	public function remove($id)
	{
		if (!$this->_options['caching']) {
			return true;
		}
		$id = $this->_id($id); // cache id may need prefix
		self::_validateIdOrTag($id);
		return $this->_backend->remove($id);
	}

	/**
	 * Clean cache entries
	 *
	 * Available modes are :
	 * 'all' (default)  => remove all cache entries ($tags is not used)
	 * 'old'            => remove too old cache entries ($tags is not used)
	 * 'matchingTag'    => remove cache entries matching all given tags
	 *                     ($tags can be an array of strings or a single string)
	 * 'notMatchingTag' => remove cache entries not matching one of the given tags
	 *                     ($tags can be an array of strings or a single string)
	 * 'matchingAnyTag' => remove cache entries matching any given tags
	 *                     ($tags can be an array of strings or a single string)
	 *
	 * @param  string       $mode
	 * @param  array|string $tags
	 * @throws Zend_Cache_Exception
	 * @return boolean True if ok
	 */
	public function clean($mode = 'all', $tags = array())
	{
		if (!$this->_options['caching']) {
			return true;
		}
		if (!in_array($mode, array(Zend_Cache::CLEANING_MODE_ALL,
		Zend_Cache::CLEANING_MODE_OLD,
		Zend_Cache::CLEANING_MODE_MATCHING_TAG,
		Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG,
		Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG))) {
			Zend_Cache::throwException('Invalid cleaning mode');
		}
		self::_validateTagsArray($tags);
		return $this->_backend->clean($mode, $tags);
	}

	/**
	 * Return an array of stored cache ids which match given tags
	 *
	 * In case of multiple tags, a logical AND is made between tags
	 *
	 * @param array $tags array of tags
	 * @return array array of matching cache ids (string)
	 */
	public function getIdsMatchingTags($tags = array())
	{
		if (!$this->_extendedBackend) {
			Zend_Cache::throwException('Current backend doesn\'t implement the Zend_Cache_Backend_ExtendedInterface, so this method is not available');
		}
		if (!($this->_backendCapabilities['tags'])) {
			Zend_Cache::throwException('tags are not supported by the current backend');
		}
		return $this->_backend->getIdsMatchingTags($tags);
	}

	/**
	 * Return an array of stored cache ids which don't match given tags
	 *
	 * In case of multiple tags, a logical OR is made between tags
	 *
	 * @param array $tags array of tags
	 * @return array array of not matching cache ids (string)
	 */
	public function getIdsNotMatchingTags($tags = array())
	{
		if (!$this->_extendedBackend) {
			Zend_Cache::throwException('Current backend doesn\'t implement the Zend_Cache_Backend_ExtendedInterface, so this method is not available');
		}
		if (!($this->_backendCapabilities['tags'])) {
			Zend_Cache::throwException('tags are not supported by the current backend');
		}
		return $this->_backend->getIdsNotMatchingTags($tags);
	}

	/**
	 * Return an array of stored cache ids
	 *
	 * @return array array of stored cache ids (string)
	 */
	public function getIds()
	{
		if (!$this->_extendedBackend) {
			Zend_Cache::throwException('Current backend doesn\'t implement the Zend_Cache_Backend_ExtendedInterface, so this method is not available');
		}
		$array = $this->_backend->getIds();
		if ((!isset($this->_options['cache_id_prefix'])) || ($this->_options['cache_id_prefix'] == '')) return $array;
		// we need to remove cache_id_prefix from ids (see #ZF-6178)
		$res = array();
		while (list(,$id) = each($array)) {
			if (strpos($id, $this->_options['cache_id_prefix']) === 0) {
				$res[] = preg_replace("~^{$this->_options['cache_id_prefix']}~", '', $id);
			} else {
				$res[] = $id;
			}
		}
		return $res;
	}

	/**
	 * Return an array of stored tags
	 *
	 * @return array array of stored tags (string)
	 */
	public function getTags()
	{
		if (!$this->_extendedBackend) {
			Zend_Cache::throwException('Current backend doesn\'t implement the Zend_Cache_Backend_ExtendedInterface, so this method is not available');
		}
		if (!($this->_backendCapabilities['tags'])) {
			Zend_Cache::throwException('tags are not supported by the current backend');
		}
		return $this->_backend->getTags();
	}

	/**
	 * Return the filling percentage of the backend storage
	 *
	 * @return int integer between 0 and 100
	 */
	public function getFillingPercentage()
	{
		if (!$this->_extendedBackend) {
			Zend_Cache::throwException('Current backend doesn\'t implement the Zend_Cache_Backend_ExtendedInterface, so this method is not available');
		}
		return $this->_backend->getFillingPercentage();
	}

	/**
	 * Return an array of metadatas for the given cache id
	 *
	 * The array will include these keys :
	 * - expire : the expire timestamp
	 * - tags : a string array of tags
	 * - mtime : timestamp of last modification time
	 *
	 * @param string $id cache id
	 * @return array array of metadatas (false if the cache id is not found)
	 */
	public function getMetadatas($id)
	{
		if (!$this->_extendedBackend) {
			Zend_Cache::throwException('Current backend doesn\'t implement the Zend_Cache_Backend_ExtendedInterface, so this method is not available');
		}
		$id = $this->_id($id); // cache id may need prefix
		return $this->_backend->getMetadatas($id);
	}

	/**
	 * Give (if possible) an extra lifetime to the given cache id
	 *
	 * @param string $id cache id
	 * @param int $extraLifetime
	 * @return boolean true if ok
	 */
	public function touch($id, $extraLifetime)
	{
		if (!$this->_extendedBackend) {
			Zend_Cache::throwException('Current backend doesn\'t implement the Zend_Cache_Backend_ExtendedInterface, so this method is not available');
		}
		$id = $this->_id($id); // cache id may need prefix
		return $this->_backend->touch($id, $extraLifetime);
	}

	/**
	 * Validate a cache id or a tag (security, reliable filenames, reserved prefixes...)
	 *
	 * Throw an exception if a problem is found
	 *
	 * @param  string $string Cache id or tag
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	protected static function _validateIdOrTag($string)
	{
		if (!is_string($string)) {
			Zend_Cache::throwException('Invalid id or tag : must be a string');
		}
		if (substr($string, 0, 9) == 'internal-') {
			Zend_Cache::throwException('"internal-*" ids or tags are reserved');
		}
		if (!preg_match('~^[\w]+$~D', $string)) {
			Zend_Cache::throwException("Invalid id or tag '$string' : must use only [a-zA-Z0-9_]");
		}
	}

	/**
	 * Validate a tags array (security, reliable filenames, reserved prefixes...)
	 *
	 * Throw an exception if a problem is found
	 *
	 * @param  array $tags Array of tags
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	protected static function _validateTagsArray($tags)
	{
		if (!is_array($tags)) {
			Zend_Cache::throwException('Invalid tags array : must be an array');
		}
		foreach($tags as $tag) {
			self::_validateIdOrTag($tag);
		}
		reset($tags);
	}

	/**
	 * Make sure if we enable logging that the Zend_Log class
	 * is available.
	 * Create a default log object if none is set.
	 *
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	protected function _loggerSanity()
	{
		if (!isset($this->_options['logging']) || !$this->_options['logging']) {
			return;
		}

		if (isset($this->_options['logger']) && $this->_options['logger'] instanceof Zend_Log) {
			return;
		}

		// Create a default logger to the standard output stream
		require_once 'Zend/Log/Writer/Stream.php';
		$logger = new Zend_Log(new Zend_Log_Writer_Stream('php://output'));
		$this->_options['logger'] = $logger;
	}

	/**
	 * Log a message at the WARN (4) priority.
	 *
	 * @param string $message
	 * @throws Zend_Cache_Exception
	 * @return void
	 */
	protected function _log($message, $priority = 4)
	{
		if (!$this->_options['logging']) {
			return;
		}
		if (!(isset($this->_options['logger']) || $this->_options['logger'] instanceof Zend_Log)) {
			Zend_Cache::throwException('Logging is enabled but logger is not set');
		}
		$logger = $this->_options['logger'];
		$logger->log($message, $priority);
	}

	/**
	 * Make and return a cache id
	 *
	 * Checks 'cache_id_prefix' and returns new id with prefix or simply the id if null
	 *
	 * @param  string $id Cache id
	 * @return string Cache id (with or without prefix)
	 */
	protected function _id($id)
	{
		if (($id !== null) && isset($this->_options['cache_id_prefix'])) {
			return $this->_options['cache_id_prefix'] . $id; // return with prefix
		}
		return $id; // no prefix, just return the $id passed
	}

}
